There is nothing called like life duration calculations in electronics design. Its the reliability which is estimated or tested in time. Generally used terms are FIT, MTBF, MTTF and MTTR.
There are different softwares and MS excel based calculators for estimating these parameters for a given design.
Following links provides good starting point in getting familiarization with reliability calculations. https://www.vicorpower.com/documents/quality/Rel_MTBF.pdf https://www.weibull.com/hotwire/issue79/relbasics79.htm
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